An acetylacetone metal salt such as acetylacetone calcium, acetylacetone magnesium and acetylacetone zinc has long been known as an effective stabilizer for a chlorine-containing resin composition, in particular, a vinyl chloride-based resin composition containing vinyl chloride as a monomer unit (See Patent Documents 1 and 2).
A stabilizer for a vinyl chloride resin composition has been very often used in production of vinyl chloride resin composition as a so-called one pack in the form of a powder or granular material, that is, a stabilizer composition comprising a lubricant or other additives as well as such a stabilizer (see Patent Document 2).
The stabilizer composition comprising the above-mentioned acetylacetone metal salt as a stabilizer is obtained as a powder material or a mixture usually by mixing the acetylacetone metal salt together with a lubricant or other additives and, if necessary, other stabilizers, at room temperature. The stabilizer composition is obtained also as a granular material when the mixture is heated and granulated (see Patent Document 2).
As a stabilizer composition comprising the above-mentioned acetylacetone metal salt, there is known such a composition comprising, for example, acetylacetone calcium, wax, a diester of a saturated fatty acid of a polyhydric alcohol (for example, pentaerythritol distearate) and zinc stearate (See Patent Document 1).
As described above, the acetylacetone metal salt is useful as a stabilizer for a vinyl chloride resin composition, but on the other hand, it is known that it has various problems (see Patent Document 3).
In the course of research aiming at improving the performance of the acetylacetone metal salt and the stabilizer composition comprising the acetylacetone metal salt, the present inventors have found that the conventionally known acetylacetone metal salt deteriorates in the performance as a stabilizer over time. They have also found that, as mentioned above, while a stabilizer composition is produced in the form of granular product by mixing the acetylacetone metal salt with other ingredients, heating and granulating the resulting mixture, the acetylacetone metal salt used is in many cases decomposed to deteriorate in the performance as a stabilizer so that a stabilizer composition that stably maintains the acetylacetone metal salt without such decomposition cannot be obtained. The inventors have further found that when a vinyl chloride resin composition comprising such a known acetylacetone metal salt or a stabilizer composition containing the same is heated and molded, the resulting molded article is accompanied by undesirable thermal coloration.
A stabilizer composition comprising the aforementioned acetylacetone metal salt and a wax and zinc stearate also has the same problem.